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The inbred—betrayed by scent?
April 17, 2008
Courtesy Current Biology
and World Science staff
Female mice can avoid inbred males based on scent alone, according to new research whose authors say the same might be true of other species. The whiff of inbreeding? New research suggests female mice avoid inbred males based on scent alone. (Image courtesy U.S. Nat'l Inst. of
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More inbred mice produce a skimpier variety of a type of molecule called major urinary proteins, or MUPs—and whose whiff betrays the shortcoming, according to the group.
“Female mice can identify more outbred males by the higher diversity of urinary proteins,” said Michael Thom of the University of Liverpool, U.K., one of the scientists. The findings appear April 17 in the online issue of the research journal
Current Biology.
Earlier, the same group found wild mice use the proteins to detect and avoid mating with close relatives. Analogous mechanisms have been
noted in humans. But the new study was different in that it examined how animals may steer clear of potential mates who are themselves inbred.
Many animals instinctively avoid inbreeding, as it creates offspring with diminished genetic variety, resulting in potential defects and health problems. But sometimes these flaws emerge only in later generations, not the first. This
raises the question of how one might avoid mating not only with one’s relatives, but with non-relatives who are healthy, yet inbred.
Female mice may do this “simply by ‘counting’ the number of proteins
[males] produce, without waiting to see which might win in a fight,” said Thorn. MUPs were already known to have functions in information signaling within the body, he added, so the new research suggests they also serve as “signals” for other individuals.
The findings are the first evidence that females can recognize inbred males based on indicators that don’t directly reflect health, he continued, adding that
similar mechanisms might be widespread among animals, including
humans.
For the study, the researchers—led by Jane Hurst, also of the university—specially bred male mice to eliminate a normal relationship between MUP variety and overall genetic diversity. The purpose was to make sure female mice would choose based on the urinary proteins, rather than on other, perhaps unknown indicators of genetic quality.
The unkind irony, in fact, was that all the male mice used were inbred. This was deliberate to ensure they had a uniform genetic makeup, further reducing females’ ability to choose based on anything but MUPs. The males were also kept apart so that females couldn’t discriminate by fighting ability. The female mice went for MUP-rich mates significantly more often than others, the investigators found.
Using similar methods, the scientists also tested whether mice might detect inbreeding based on another set of molecules, called the major histocompatibility complex. These are those that in humans are believed to operate for
avoiding related partners, again through scent. But these proteins didn’t seem relevant in the
mouse case, the investigators said.
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Female mice can avoid inbred males based on scent alone, according to new research whose authors say the same might be true of other species. Inbred mice produce a skimpier variety of a type of molecule called major urinary proteins, or MUPs—and whose whiff betrays the shortcoming, according to the group. “Female mice can identify more outbred males by the higher diversity of urinary proteins,” said Michael Thom of the University of Liverpool, U.K., one of the scientists. The findings appear April 17 in the online issue of the research journal Current Biology. An earlier study by the same group found wild mice use the proteins to detect and avoid mating with close relatives. Analogous mechanisms have been found in humans. But the new study was different in that it examined how animals may steer clear of potential mates who are themselves inbred. Many animals instinctively avoid inbreeding because it creates offspring with diminished genetic variety, resulting in potential defects and health problems. But sometimes these flaws emerge only in later generations, not the first offspring. This leaves the problem of how to avoid mating not only with relatives, but with non-relatives who are healthy, yet inbred. Female mice may thus spot “superior males simply by ‘counting’ the number of proteins they produce, without waiting to see which might win in a fight,” said Thorn. MUPs were already known to have functions in information signaling within the body, he added, so the new research suggests they also serve as “signals” for other individuals. The findings are the first evidence that females can recognize inbred males based on indicators that don’t directly reflect their health, he continued, adding that again, similar mechanisms might be widespread among animals. For the study, the researchers—led by Jane Hurst, also of the university—specially bred male mice to eliminate a normal relationship between MUP variety and overall genetic diversity. The purpose was to make sure female mice would choose based on the urinary proteins, rather than on other, perhaps unknown indicators of genetic quality. The unkind irony, in fact, was that all the male mice were inbred. This was deliberate to ensure they had a uniform genetic makeup, further reducing females’ ability to choose based on anything but MUPs. The males were also kept apart so that females couldn’t discriminate by fighting ability. The female mice went for MUP-rich mates significantly more often than others, the investigators found. Using similar methods, the scientists also tested whether mice might detect inbreeding based on another set of molecules, called the major histocompatibility complex. These are those that in humans are believed to operate for avoiding related partners, again through scent. But these proteins didn’t seem relevant in the mice, the investigators said.